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随着甚长基线干涉测量(VLBI)、卫星激光测距(SLR)、激光测月(LLR)、全球卫星导航系统(GNSS)、多里斯系统(DORIS)等多种空间大地测量手段的使用,地球自转参数(ERP)的测量精度不断提高,为航天器导航、深空探测等诸多领域提供了高精度的国际天球参考系(ICRS)和国际地表参考系统(ITRS)之间的转换参数. 以国际地球自转与参考系服务发布的C04序列为基础序列,选取500天ERP序列,分析不同测量手段得到的ERP数据的误差分布情况,为研究利用不同数据之间的一致性进行精度检核的可行性及精度水平提供数据基础,同时也为ERP预报提供更多的数据选择. 相似文献
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Multi-technique comparison of tropospheric zenith delays derived during the CONT02 campaign 总被引：2，自引：7，他引：2
In October 2002, 15 continuous days of Very Long Baseline Interferometry (VLBI) data were observed in the Continuous VLBI 2002 (CONT02) campaign. All eight radio telescopes involved in CONT02 were co-located with at least one other space-geodetic technique, and three of them also with a Water Vapor Radiometer (WVR). The goal of this paper is to compare the tropospheric zenith delays observed during CONT02 by VLBI, Global Positioning System (GPS), Doppler Orbitography Radiopositioning Integrated by Satellite (DORIS) and WVR and to compare them also with operational pressure level data from the European Centre for Medium-Range Weather Forecasts (ECMWF). We show that the tropospheric zenith delays from VLBI and GPS are in good agreement at the 3–7 mm level. However, while only small biases can be found for most of the stations, at Kokee Park (Hawaii, USA) and Westford (Massachusetts, USA) the zenith delays derived by GPS are larger by more than 5 mm than those from VLBI. At three of the four DORIS stations, there is also a fairly good agreement with GPS and VLBI (about 10 mm), but at Kokee Park the agreement is only at about 30 mm standard deviation, probably due to the much older installation and type of DORIS equipment. This comparison also allows testing of different DORIS analysis strategies with respect to their real impact on the precision of the derived tropospheric parameters. Ground truth information about the zenith delays can also be obtained from the ECMWF numerical weather model and at three sites using WVR measurements, allowing for comparisons with results from the space-geodetic techniques. While there is a good agreement (with some problems mentioned above about DORIS) among the space-geodetic techniques, the comparison with WVR and ECMWF is at a lower accuracy level. The complete CONT02 data set is sufficient to derive a good estimate of the actual precision and accuracy of each geodetic technique for applications in meteorology. 相似文献
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The AuScope geodetic VLBI array 总被引：1，自引：1，他引：0
J. E. J. Lovell J. N. McCallum P. B. Reid P. M. McCulloch B. E. Baynes J. M. Dickey S. S. Shabala C. S. Watson O. Titov R. Ruddick R. Twilley C. Reynolds S. J. Tingay P. Shield R. Adada S. P. Ellingsen J. S. Morgan H. E. Bignall 《Journal of Geodesy》2013,87(6):527-538
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In geodetic and geophysical applications of GPS, it is important to realize the ephemerides of the GPS satellites and the coordinates of station positions in a consistent reference system. At present, more than one reference system is being used by various GPS users depending on their specific applications. The WGS-84 and various reference frames based on satellite laser ranging (SLR), very long baseline interferometry (VLBI), or a combination of SLR and VLBI are the most commonly used in high precision geophysical applications. The WGS-84 is widely used in applications which rely on the GPS broadcast ephemeris. Station coordinates estimated in one system may have to be transformed to another for further use or for evaluation/comparison purposes. This paper presents a seven-parameter transformation between the WGS-84 and SLR/VLBI reference frames. The GPS double-differenced phase measurements for two consecutive weeks from a set of five Defense Mapping Agency (DMA) sites (defined in the WGS-84 frame) and from an augmented set of fifteen CIGNET sites (defined in the SLR/VLBI frame) were processed in a least squares estimation scheme to determine station coordinates, from which the transformation parameters were determined. A scale difference of about 0.2 ppm and an orientation difference in longitude of about 31 milliarcseconds were found to be the only parameters of significance between the adopted SLR/VLBI and the WGS-84 frames. Transformation between WGS-84 and the ITRF90 is also included, in which the scale difference is the same as before but the longitude rotation is about 16 mas. 相似文献
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The paper presents the results of crustal deformation, as evidenced by changed station coordinates, in the Tokyo metropolitan area detected by the satellite laser ranging (SLR) technique. The coordinates of two Key Stone SLR stations, Tateyama and Kashima, were determined from 4 weeks of orbital arcs of the LAGEOS-1 and LAGEOS-2 satellites with respect to 16 SLR stations kept fixed in the ITRF2000 reference frame. The station coordinates were calculated using the NASA GEODYN-II orbital program. The orbital RMS-of-fit for both satellites was 16 mm. The standard deviation of the estimated positions was 3 mm. A jump of about 5 cm in the baseline length between the Kashima and Tateyama stations was detected in June–August 2000 by VLBI and GPS techniques. This work confirms this crustal deformation as determined by SLR and vice versa. Analysis of coordinates of these stations shows that this effect was caused by a 4.5-cm displacement of the Tateyama station in the north-east direction. The change in the vertical component was not significant. 相似文献
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CONT campaigns are 2-week campaigns of continuous VLBI observations. The IERS working group on combination at the observation level uses these campaigns to study such combinations. In this work, combinations of DORIS, GPS, SLR, and VLBI technique measurements are studied during CONT08. We present different results concerning the use of common zenith tropospheric delay (ZTD) during the combination. We compare the ZTD obtained separately using each individual technique data processing, the combined ZTD, and the ZTD derived from a meteorological model. This resulted in a high level of consistency between each of these ZTD at a sub-centimeter level, a consistency which especially depends on the number of observations per estimated ZTD and the humidity level in the troposphere. We noted that GPS provides the main information about the combined ZTD, the other techniques providing complementary information when a lack of GPS observations occurs. 相似文献
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The 2008 DGFI realization of the ITRS: DTRF2008 总被引：11，自引：11，他引：0
Manuela Seitz Detlef Angermann Mathis Blo?feld Hermann Drewes Michael Gerstl 《Journal of Geodesy》2012,86(12):1097-1123
A new realization of the International Terrestrial System was computed at the ITRS Combination Centre at DGFI as a contribution to ITRF2008. The solution is labelled DTRF2008. In the same way as in the DGFI computation for ITRF2005 it is based on either normal equation systems or estimated parameters derived from VLBI, SLR, GPS and DORIS observations by weekly or session-wise processing. The parameter space of the ITRS realization comprises station positions and velocities and daily resolved Earth Orientation Parameters (EOP), whereby for the first time also nutation parameters are included. The advantage of starting from time series of input data is that the temporal behaviour of geophysical parameters can be investigated to decide whether the parameters can contribute to the datum realization of the ITRF. In the same way, a standardized analysis of station position time series can be performed to detect and remove discontinuities. The advantage of including EOP in the ITRS realization is twofold: (1) the combination of the coordinates of the terrestrial pole—estimated from all contributing techniques—links the technique networks in two components of the orientation, leading to an improvement of consistency of the Terrestrial Reference Frame (TRF) and (2) in their capacity as parameters common to all techniques, the terrestrial pole coordinates enhance the selection of local ties as they provide a measure for the consistency of the combined frame. The computation strategy of DGFI is based on the combination of normal equation systems while at the ITRS Combination Centre at IGN solutions are combined. The two independent ITRS realizations provide the possibility to assess the accuracy of ITRF by comparison of the two frames. The accuracy evaluation was done separately for the datum parameters (origin, orientation and scale) and the network geometry. The accuracy of the datum parameters, assessed from the comparison of DTRF2008 and ITRF2008, is between 2–5?mm and 0.1–0.8?mm/year depending on the technique. The network geometry (station positions and velocities) agrees within 3.2?mm and 1.0?mm/year. A comparison of DTRF2008 and ITRF2005 provides similar results for the datum parameters, but there are larger differences for the network geometry. The internal accuracy of DTRF2008—that means the level of conservation of datum information and network geometry within the combination—was derived from comparisons with the technique-only multi-year solutions. From this an internal accuracy of 0.32?mm for the VLBI up to 3.3?mm for the DORIS part of the network is found. The internal accuracy of velocities ranges from 0.05?mm/year for VLBI to 0.83?mm/year for DORIS. The internal consistency of DTRF2008 for orientation can be derived from the analysis of the terrestrial pole coordinates. It is estimated at 1.5–2.5?mm for the GPS, VLBI and SLR parts of the network. The consistency of these three and the DORIS network part is within 6.5?mm. 相似文献
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Claudio Abbondanza Zuheir Altamimi Pierguido Sarti Monia Negusini Luca Vittuari 《Journal of Geodesy》2009,83(11):1031-1040
Tie vectors (TVs) between co-located space geodetic instruments are essential for combining terrestrial reference frames (TRFs)
realised using different techniques. They provide relative positioning between instrumental reference points (RPs) which are
part of a global geodetic network such as the international terrestrial reference frame (ITRF). This paper gathers the set
of very long baseline interferometry (VLBI)–global positioning system (GPS) local ties performed at the observatory of Medicina
(Northern Italy) during the years 2001–2006 and discusses some important aspects related to the usage of co-location ties
in the combinations of TRFs. Two measurement approaches of local survey are considered here: a GPS-based approach and a classical
approach based on terrestrial observations (i.e. angles, distances and height differences). The behaviour of terrestrial local
ties, which routinely join combinations of space geodetic solutions, is compared to that of GPS-based local ties. In particular,
we have performed and analysed different combinations of satellite laser ranging (SLR), VLBI and GPS long term solutions in
order to (i) evaluate the local effects of the insertion of the series of TVs computed at Medicina, (ii) investigate the consistency
of GPS-based TVs with respect to space geodetic solutions, (iii) discuss the effects of an imprecise alignment of TVs from
a local to a global reference frame. Results of ITRF-like combinations show that terrestrial TVs originate the smallest residuals
in all the three components. In most cases, GPS-based TVs fit space geodetic solutions very well, especially in the horizontal
components (N, E). On the contrary, the estimation of the VLBI RP Up component through GPS technique appears to be awkward,
since the corresponding post fit residuals are considerably larger. Besides, combination tests including multi-temporal TVs
display local effects of residual redistribution, when compared to those solutions where Medicina TVs are added one at a time.
Finally, the combination of TRFs turns out to be sensitive to the orientation of the local tie into the global frame. 相似文献
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采用HY2A卫星2013年2月的实测数据,研究了GPS、星载多谱勒无线电定轨定位系统(DORIS)及卫星激光测距(SLR)三种观测数据的单独和联合定轨问题。通过与法国CNES的精密轨道数据比较发现:分别采用GPS、DORIS和SLR数据进行单独定轨,GPS数据确定轨道的径向平均精度为1.3cm,三维位置约为6.2cm;DORIS定轨的径向平均精度为1.6cm,比GPS结果略差;SLR确定轨道的径向平均精度为2.3cm。用GPS、DORIS和SLR三种数据联合定轨,确定轨道的径向平均精度为1.2cm,三维位置约为6.5cm。与星载GPS定轨结果比较,三种观测数据的联合定轨在提高卫星轨道确定精度上不明显,但联合定轨有利于保持计算轨道精度相对稳定。用站星间高度角大于60°的SLR数据检验GPS/DORIS联合确定的轨道,两者在测距方向的均方差为2.5cm,可见基于HY2A的观测数据可以实现cm级的定轨需求。 相似文献
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从全球国际地球参考框架（International Terrestrial Reference Frame，ITRF）的建立、维护与发展，卫星测高、卫星重力等的发展及应用，全球卫星导航系统（Global Navigation Satellite System，GNSS）、卫星激光测距（Satellite Laser Ranging，SLR）、甚长基线干涉测量（very Long Baseline Interferometry，VLBI）、卫星多普勒定轨定位（Doppler Orbitography by Radiopositioning Integrated on Satellite，DORIS）的融合应用，海洋测绘和室内定位的发展等几个方面综述了大地测量学及卫星导航定位技术的最新进展，并提出中国2000国家大地坐标系与自主卫星导航系统的主要应用及发展目标。 相似文献
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ITRF2000和新的全球板块运动模型 总被引：6，自引：0，他引：6
地学工作者一直关注的ITRF2000地球参考框架初步结果已于2001年3月19日公布，ITRF2000综合了VLBI、SLR，LLR，GPS和DORIS技术，产生736个点位坐标和54个核心站，文中介绍了ITRF2000，并利用ITRF2000综合解的结果计算全球板块的欧拉矢量，建立了基于空间实测数据基础 的最新全球板块运动模型。 相似文献
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针对GPS、SLR和DORIS三种不同手段的各自定轨精度问题,本文基于不同的轨道评估方法进行了深入分析。以JASON-2卫星为例,分析了姿态模型误差及其对定轨精度的影响,分别讨论了GPS、SLR和DORIS的定轨策略和定轨精度,并基于轨道评估结果进行了轨道叠加。基于实测数据进行了试验,试验结果表明,JASON-2卫星姿态模型误差对DORIS、GPS和SLR轨道影响分别为0.040、0.036和0.033m;DORIS定轨结果优于GPS和SLR,SLR定轨精度最差;基于SLR验证和轨道重叠结果加权,对GPS、SLR和DORIS轨道进行轨道叠加,其精度一致,通过与JPL轨道比较,其径向精度为2cm。 相似文献
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Height bias and scale effect induced by antenna gravitational deformations in geodetic VLBI data analysis 总被引：2，自引：2，他引：0
The impact of signal path variations (SPVs) caused by antenna gravitational deformations on geodetic very long baseline interferometry
(VLBI) results is evaluated for the first time. Elevation-dependent models of SPV for Medicina and Noto (Italy) telescopes
were derived from a combination of terrestrial surveying methods to account for gravitational deformations. After applying
these models in geodetic VLBI data analysis, estimates of the antenna reference point positions are shifted upward by 8.9
and 6.7 mm, respectively. The impact on other parameters is negligible. To simulate the impact of antenna gravitational deformations
on the entire VLBI network, lacking measurements for other telescopes, we rescaled the SPV models of Medicina and Noto for
other antennas according to their size. The effects of the simulations are changes in VLBI heights in the range [−3, 73] mm
and a net scale increase of 0.3–0.8 ppb. The height bias is larger than random errors of VLBI position estimates, implying
the possibility of significant scale distortions related to antenna gravitational deformations. This demonstrates the need
to precisely measure gravitational deformations of other VLBI telescopes, to derive their precise SPV models and to apply
them in routine geodetic data analysis. 相似文献
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We assess the accuracy of some indirect approaches to invariant point (IVP), or system reference point, determination of satellite
laser ranging (SLR) and very long baseline interferometry (VLBI) systems using both observed and simulated survey data sets.
Indirect IVP determination involves the observation of targets located on these systems during specific rotational sequences
and by application of geometrical models that describe the target motion during these sequences. Of concern is that most SLR
and VLBI systems have limited rotational freedom thereby placing constraint on the reliability of parameter estimation, including
the IVP position. We assess two current approaches to IVP analysis using survey data observed at the Yarragadee (Australia)
SLR and the Medicina (Italy) VLBI sites and also simulated data of a large rotationally constrained (azimuth-elevation) VLBI
system. To improve reliability we introduce and assess some new geometric conditions, including inter-axis, inter-circle and
inter-target conditions, to existing IVP analysis strategies. The error component of a local tie specifically associated with
the indirect determination of SLR and VLBI IVP is less than 0.5 mm. For systems with significant rotational limits we find
that the inter-axis and inter-circle conditions are critical to the computation of unbiased IVP coordinates at the sub-millimetre
level. When the inter-axis and inter-circle geometric conditions are not imposed, we retrieve biased vertical coordinates
of the IVP (in our simulated VLBI system) in the range of 1.2–3.4 mm. Using the new geometric conditions we also find that
the axis-offset estimates can be recovered at the sub- millimetre accuracy (0.5 mm). 相似文献